$baseFontSize:14px;

@mixin min-screen($screen) {
    @media only screen and ( min-width: $screen)
    {
        @content;
    }
}

@for $i from 32 through 100{
    @include min-screen($i*10+px){
        .con_top p{font-size:$i/20*10+px}
        .con_top p span{font-size:$i/10*10+px}
        .product_in tbody th{font-size:$i/20*10+px}
        .product_in tbody td{font-size:$i/25*10+px}
    }
}